The basking shark (''Cetorhinus maximus'') is the second-largest living
shark
Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimo ...
and
fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...
,
after the
whale shark
The whale shark (''Rhincodon typus'') is a slow-moving, filter-feeding carpet shark and the largest known extant fish species. The largest confirmed individual had a length of .McClain CR, Balk MA, Benfield MC, Branch TA, Chen C, Cosgrove J, D ...
, and one of three
plankton-eating shark species, along with the whale shark and
megamouth shark
The megamouth shark (''Megachasma pelagios'') is a species of deepwater shark. It is rarely seen by humans and is the smallest of the three extant taxon, extant filter-feeding sharks alongside the relatively larger whale shark and basking shark. ...
. Adults typically reach in length. It is usually greyish-brown, with mottled skin, with the inside of the mouth being white in color. The
caudal fin
Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...
has a strong lateral keel and a crescent shape. Other common names include bone shark, elephant shark, sail-fish, and sun-fish. In
Orkney
Orkney (; sco, Orkney; on, Orkneyjar; nrn, Orknøjar), also known as the Orkney Islands, is an archipelago in the Northern Isles of Scotland, situated off the north coast of the island of Great Britain. Orkney is 10 miles (16 km) north ...
, it is commonly known as hoe-mother (sometimes contracted to homer), meaning "the mother of the pickled dog-fish".
The basking shark is a
cosmopolitan
Cosmopolitan may refer to:
Food and drink
* Cosmopolitan (cocktail), also known as a "Cosmo"
History
* Rootless cosmopolitan, a Soviet derogatory epithet during Joseph Stalin's anti-Semitic campaign of 1949–1953
Hotels and resorts
* Cosmopoli ...
migratory species, found in all the world's temperate oceans. A slow-moving
filter feeder, its common name derives from its habit of feeding at the surface, appearing to be basking in the warmer water there. It has anatomical adaptations for filter-feeding, such as a greatly enlarged mouth and highly developed
gill rakers
Gill rakers in fish are bony or cartilaginous processes that project from the branchial arch (gill arch) and are involved with suspension feeding tiny prey. They are not to be confused with the gill filaments that compose the fleshy part of t ...
. Its snout is conical and the gill slits extend around the top and bottom of its head. The gill rakers, dark and bristle-like, are used to catch plankton as water filters through the mouth and over the gills. The teeth are numerous and very small, and often number 100 per row. The teeth have a single conical cusp, are curved backwards and are the same on both the upper and lower jaws. This species has the smallest weight-for-weight brain size of any shark, reflecting its relatively passive lifestyle.
Basking sharks have been shown from satellite tracking to
overwinter
Overwintering is the process by which some organisms pass through or wait out the winter season, or pass through that period of the year when "winter" conditions (cold or sub-zero temperatures, ice, snow, limited food supplies) make normal acti ...
in both continental shelf (less than ) and deeper waters.
They may be found in either small shoals or alone. Despite their large size and threatening appearance, basking sharks are not aggressive and are harmless to humans.
The basking shark has long been a
commercially important fish as a source of food,
shark fin, animal feed, and
shark liver oil
Shark liver oil is an oil obtained from the livers of sharks. It has been used for centuries as a folk remedy to promote the healing of wounds and as a remedy for respiratory tract and digestive system problems. .
Overexploitation
Overexploitation, also called overharvesting, refers to harvesting a renewable resource to the point of diminishing returns. Continued overexploitation can lead to the destruction of the resource, as it will be unable to replenish. The term app ...
has reduced its populations to the point where some have disappeared and others need protection.
Taxonomy
The basking shark is the only
extant member of the family
Cetorhinidae, part of the mackerel shark order
Lamniformes
The Lamniformes (, from Greek ''lamna'' "fish of prey") are an order (biology), order of sharks commonly known as mackerel sharks (which may also refer specifically to the family Lamnidae). It includes some of the most familiar species of sharks, ...
.
Johan Ernst Gunnerus
Johan Ernst Gunnerus (26 February 1718 – 25 September 1773) was a Norwegian bishop and botanist. Gunnerus was born at Christiania. He was bishop of the Diocese of Nidaros from 1758 until his death and also a professor of theology at the Univer ...
first described the species as ''Cetorhinus maximus'', from a specimen found in
Norway
Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...
, naming it. The genus name ''Cetorhinus'' comes from the Greek ''ketos'', meaning "marine monster" or "whale", and ''rhinos'', meaning "nose". The species name ''maximus'' is from Latin and means "greatest". Following its initial description, more attempts at naming included: ''Squalus isodus'', in 1819 by Italian Zoologist Saverio Macri (1754–1848); ''Squalus elephas'', by
Charles Alexandre Lesueur
Charles Alexandre Lesueur (1 January 1778 in Le Havre – 12 December 1846 in Le Havre) was a French naturalist, artist, and explorer. He was a prolific natural-history collector, gathering many type specimens in Australia, Southeast Asia, ...
in 1822; ''Squalus rashleighanus'', by
Jonathan Couch
Jonathan Couch (15 March 1789 – 13 April 1870) was a British naturalist, the only child of Richard and Philippa Couch, of a family long resident at Polperro, a small fishing village between Looe and Fowey, on the south coast of Cornwall. A ...
in 1838; ''Squalus cetaceus'', by
Laurens Theodorus Gronovius
Laurens Theodoor Gronovius (1 June 1730 – 8 August 1777), also known as Laurentius Theodorus Gronovius or as Laurens Theodoor Gronow, was a Dutch naturalist born in Leiden. He was the son of botanist Jan Frederik Gronovius (1686–1762).
Thro ...
in 1854; ''Cetorhinus blainvillei'' by the Portuguese biologist Felix Antonio de Brito Capello (1828–1879) in 1869; ''Selachus pennantii'', by
Charles John Cornish
Charles John Cornish (28 September 1858 – 30 January 1906) was an English naturalist and author. Life
Born on 28 September 1858 at Salcombe House, near Sidmouth, the residence of his grandfather, Charles John Cornish, J.P., D.L., was eldest son ...
in 1885; ''Cetorhinus maximus infanuncula'', by the Dutch Zoologists Antonius Boudewijn Deinse (1885–1965) and Marcus Jan Adriani (1929–1995) in 1953; and ''Cetorhinus maximus normani'', by Siccardi in 1961.
Evolutionary history
The oldest known members of Cetorhinidae are members of the extinct genus ''
Keasius
''Keasius'' is an extinct genus of basking sharks that lived during the Cenozoic. It contains four valid species, which have been found in North America, Europe, and Antarctica
Antarctica () is Earth's southernmost and least-populated c ...
,'' from middle
Eocene
The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...
of Antarctica, the Eocene of Oregon and possibly the Eocene of Russia. Members of the modern genus ''Cetorhinus'' appear during the
Miocene
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
, with members of the modern species appearing during the Late Miocene. The association of ''
Pseudocetorhinus'' from the Late Triassic of Europe with Cetorhinidae is doubtful.
Range and habitat
The basking shark is a coastal-
pelagic
The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...
shark found worldwide in
boreal to warm-temperate waters. It lives around the
continental shelf
A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...
and occasionally enters
brackish water
Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estua ...
s.
It is found from the surface down to at least . It prefers temperatures of , but has been confirmed to cross the much-warmer waters at the equator.
It is often seen close to land, including in bays with narrow openings. The shark follows
plankton
Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...
concentrations in the water column, so is often visible at the surface. It characteristically migrates with the seasons.
Anatomy and appearance
The basking shark regularly reaches in length with some individuals reaching .
The average length of an adult is around weighing about .
Historical sightings suggest basking sharks around in length, including three basking sharks estimated at ~40
fod () and a one ~45 fod () were reported between 1884 and 1905, but these visual estimates lack good evidence.
A specimen trapped in a herring net in the
Bay of Fundy
The Bay of Fundy (french: Baie de Fundy) is a bay between the Canadian provinces of New Brunswick and Nova Scotia, with a small portion touching the U.S. state of Maine. It is an arm of the Gulf of Maine. Its extremely high tidal range is the hi ...
, Canada, in 1851 has been credited as the largest recorded.
[McClain CR, Balk MA, Benfield MC, Branch TA, Chen C, Cosgrove J, Dove ADM, Gaskins LC, Helm RR, Hochberg FG, Lee FB, Marshall A, McMurray SE, Schanche C, Stone SN, Thaler AD. 2015. Sizing ocean giants: patterns of intraspecific size variation in marine megafauna. ''PeerJ'' 3:e715 https://doi.org/10.7717/peerj.715] Its weight has been estimated at .
A study looking at the growth and longevity of the basking shark suggested that individuals larger than ~ are unlikely. This is the second-largest extant fish species, after the whale shark.
![basking shark](https://upload.wikimedia.org/wikipedia/commons/4/41/Basking_shark.png)
They possess the typical shark
lamniform body plan and have been mistaken for
great white shark
The great white shark (''Carcharodon carcharias''), also known as the white shark, white pointer, or simply great white, is a species of large Lamniformes, mackerel shark which can be found in the coastal surface waters of all the major ocean ...
s. The two species can be easily distinguished by the basking shark's cavernous jaw, up to in width, longer and more obvious
gill
A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...
slits that nearly encircle the head and are accompanied by well-developed
gill raker
Gill rakers in fish are bony or cartilaginous processes that project from the branchial arch (gill arch) and are involved with suspension feeding tiny prey. They are not to be confused with the gill filaments that compose the fleshy part of the ...
s, smaller eyes, much larger overall size and smaller average girth. Great whites possess large, dagger-like teeth; basking shark teeth are much smaller and hooked; only the first three or four rows of the upper jaw and six or seven rows of the lower jaw function. In behaviour, the great white is an active predator of large animals and not a filter feeder.
Other distinctive characteristics include a strongly keeled
caudal peduncle
Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...
, highly textured skin covered in
placoid scale
A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as ...
s and a mucus layer, a pointed snout—distinctly hooked in younger specimens—and a lunate
caudal fin
Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...
. In large individuals, the
dorsal fin
A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...
may flop to one side when above the surface. Colouration is highly variable (and likely dependent on observation conditions and the individual's condition): commonly, the colouring is dark brown to black or blue dorsally, fading to a dull white ventrally. The sharks are often noticeably scarred, possibly through encounters with
lamprey
Lampreys (sometimes inaccurately called lamprey eels) are an ancient extant lineage of jawless fish of the order Petromyzontiformes , placed in the superclass Cyclostomata. The adult lamprey may be characterized by a toothed, funnel-like s ...
s or
cookiecutter shark
The cookiecutter shark (''Isistius brasiliensis''), also called the cigar shark, is a species of small squaliform shark in the family Dalatiidae. This shark occurs in warm, oceanic waters worldwide, particularly near islands, and has been rec ...
s. The basking shark's liver, which may account for 25% of its body weight, runs the entire length of the abdominal cavity and is thought to play a role in
buoyancy
Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the p ...
regulation and long-term energy storage.
Life history
![Basking head](https://upload.wikimedia.org/wikipedia/commons/2/2c/Basking_head.jpg)
Basking sharks do not hibernate, and are active year-round.
In winter, basking sharks often move to deeper depths, even down to and have been tracked making vertical movements consistent with feeding on overwintering zooplankton.
Surfacing behaviors
They are slow-moving sharks (feeding at about ) and do not evade approaching boats (unlike great white sharks). They are not attracted to
chum.
Though the basking shark is large and slow, it can
breach
Breach, Breached, or The Breach may refer to:
Places
* Breach, Kent, United Kingdom
* Breach, West Sussex, United Kingdom
* ''The Breach'', Great South Bay in the State of New York
People
* Breach (DJ), an Electronic/House music act
* Miroslava ...
, jumping entirely out of the water.
This behaviour could be an attempt to dislodge parasites or
commensals.
Such interpretations are speculative, however, and difficult to verify; breaching in large marine animals such as whales and sharks might equally well be
intraspecific
Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species.
Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organ ...
threat display
Deimatic behaviour or startle display means any pattern of bluffing behaviour in an animal that lacks strong defences, such as suddenly displaying conspicuous eyespots, to scare off or momentarily distract a predator, thus giving the prey anima ...
s of size and strength.
Migration
Argos system
Argos is a global satellite-based system that collects, processes, and disseminates environmental data from fixed and mobile platforms around the world. The worldwide tracking and environmental monitoring system results from Franco-America ...
satellite tagging of 20 basking sharks in 2003 confirmed basking sharks move thousands of kilometres during the summer and winter, seeking the richest zooplankton patches, often along
ocean fronts.
They shed and renew their gill rakers in an ongoing process, rather than over one short period.
A 2009 study tagged 25 sharks off the coast of
Cape Cod
Cape Cod is a peninsula extending into the Atlantic Ocean from the southeastern corner of mainland Massachusetts, in the northeastern United States. Its historic, maritime character and ample beaches attract heavy tourism during the summer mont ...
,
, and indicated at least some migrate south in the winter. Remaining at depths between for many weeks, the tagged sharks crossed the equator to reach Brazil. One individual spent a month near the mouth of the
Amazon River
The Amazon River (, ; es, Río Amazonas, pt, Rio Amazonas) in South America is the largest river by discharge volume of water in the world, and the disputed longest river system in the world in comparison to the Nile.
The headwaters of t ...
. They may undertake this journey to aid reproduction.
On 23 June 2015, a , basking shark was caught accidentally by a
fishing trawler
A fishing trawler is a commercial fishing vessel designed to operate Trawling, fishing trawls. Trawling is a method of fishing that involves actively dragging or pulling a trawl through the water behind one or more trawlers. Trawls are fishing ...
in the
Bass strait
Bass Strait () is a strait separating the island state of Tasmania from the Australian mainland (more specifically the coast of Victoria, with the exception of the land border across Boundary Islet). The strait provides the most direct waterwa ...
near
Portland
Portland most commonly refers to:
* Portland, Oregon, the largest city in the state of Oregon, in the Pacific Northwest region of the United States
* Portland, Maine, the largest city in the state of Maine, in the New England region of the northeas ...
,
Victoria
Victoria most commonly refers to:
* Victoria (Australia), a state of the Commonwealth of Australia
* Victoria, British Columbia, provincial capital of British Columbia, Canada
* Victoria (mythology), Roman goddess of Victory
* Victoria, Seychelle ...
, in southeast
Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
, the first basking shark caught in the region since the 1930s, and only the third reported in the region in 160 years. The whole shark was donated to the
Victoria Museum for research, instead of the fins being sold for use in
shark fin soup
Shark fin soup is a traditional soup or stewed dish served in parts of China, Taiwan, and Southeast Asia. The shark fins provide texture, while the taste comes from the other soup ingredients. It is commonly served at special occasions such as ...
.
While basking sharks are not infrequently seen in the
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ea ...
and records exist in the
Dardanelles Strait
The Dardanelles (; tr, Çanakkale Boğazı, lit=Strait of Çanakkale, el, Δαρδανέλλια, translit=Dardanéllia), also known as the Strait of Gallipoli from the Gallipoli peninsula or from Classical Antiquity as the Hellespont ( ...
, it is unclear whether they historically reached into deeper basins of
Sea of Marmara
The Sea of Marmara,; grc, Προποντίς, Προποντίδα, Propontís, Propontída also known as the Marmara Sea, is an inland sea located entirely within the borders of Turkey. It connects the Black Sea to the Aegean Sea via the ...
,
Black Sea
The Black Sea is a marginal mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia, Roma ...
and
Azov Sea.
Social behaviour
![Basking Shark](https://upload.wikimedia.org/wikipedia/commons/0/0a/Basking_Shark.jpg)
Basking sharks are usually solitary but during summer months in particular they aggregate in dense patches of zooplankton where they engage in social behaviour. They can form sex-segregated shoals, usually in small numbers (three or four), but reportedly up to 100 individuals.
Small schools in the
Bay of Fundy
The Bay of Fundy (french: Baie de Fundy) is a bay between the Canadian provinces of New Brunswick and Nova Scotia, with a small portion touching the U.S. state of Maine. It is an arm of the Gulf of Maine. Its extremely high tidal range is the hi ...
and the
Hebrides
The Hebrides (; gd, Innse Gall, ; non, Suðreyjar, "southern isles") are an archipelago off the west coast of the Scottish mainland. The islands fall into two main groups, based on their proximity to the mainland: the Inner and Outer Hebrid ...
have been seen swimming nose to tail in circles; their social behaviour in summer months has been studied and is thought to represent courtship.
Predators
Basking sharks have few predators. White sharks have been reported to scavenge on the remains of these sharks.
Killer whale
The orca or killer whale (''Orcinus orca'') is a toothed whale belonging to the oceanic dolphin family, of which it is the largest member. It is the only extant species in the genus ''Orcinus'' and is recognizable by its black-and-white pa ...
s have been observed feeding on basking sharks off California in the US and New Zealand.
Lamprey
Lampreys (sometimes inaccurately called lamprey eels) are an ancient extant lineage of jawless fish of the order Petromyzontiformes , placed in the superclass Cyclostomata. The adult lamprey may be characterized by a toothed, funnel-like s ...
s are often seen attached to them, although they are unlikely to be able to cut through the shark's thick skin.
Diet
![BS4 small](https://upload.wikimedia.org/wikipedia/commons/7/7a/BS4_small.jpg)
The basking shark is a ram
feeder, filtering
zooplankton
Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...
, very small fish, and
invertebrate
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
s from the water with its gill rakers by swimming forwards with their mouths open. A basking shark has been calculated to filter up to of water per hour swimming at an observed speed of .
Basking sharks are not indiscriminate feeders on zooplankton. Samples taken in the presence of feeding individuals recorded zooplankton densities 75% higher compared to adjacent non-feeding areas. Basking sharks feed preferentially in zooplankton patches dominated by small planktonic crustaceans called
calanoid copepods (on average 1,700 individuals per cubic metre of water). They will also feed on copepods of the genera ''Psuedocalanus'' and ''
Oithona''. Basking sharks sometimes congregate in groups of up to 1,400 spotted along the northeastern U.S. Samples taken near feeding sharks contained 2.5 times as many ''
Calanus helgolandicus
''Calanus helgolandicus'' is a copepod found in the Atlantic, from the North Sea south to the western coast of Africa. The female has an average size of about and the male has an average size of about .
Description
The female has an average siz ...
'' individuals per cubic metre, which were also found to be 50% longer. Unlike the
megamouth shark
The megamouth shark (''Megachasma pelagios'') is a species of deepwater shark. It is rarely seen by humans and is the smallest of the three extant taxon, extant filter-feeding sharks alongside the relatively larger whale shark and basking shark. ...
and
whale shark
The whale shark (''Rhincodon typus'') is a slow-moving, filter-feeding carpet shark and the largest known extant fish species. The largest confirmed individual had a length of .McClain CR, Balk MA, Benfield MC, Branch TA, Chen C, Cosgrove J, D ...
, the basking shark relies only on the water it pushes through its gills by swimming; the megamouth shark and whale shark can suck or pump water through their gills.
Reproduction
Basking sharks are
ovoviviparous
Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop insi ...
: the developing embryos first rely on a
yolk
Among animals which produce eggs, the yolk (; also known as the vitellus) is the nutrient-bearing portion of the egg whose primary function is to supply food for the development of the embryo. Some types of egg contain no yolk, for example ...
sac, with no
placenta
The placenta is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas and waste exchange between the physically separate mater ...
l connection. Their seemingly useless teeth may play a role before birth in helping them feed on the mother's unfertilized
ova
, abbreviated as OVA and sometimes as OAV (original animation video), are Japanese animated films and series made specially for release in home video formats without prior showings on television or in theaters, though the first part of an OVA s ...
(a behaviour known as
oophagy
Oophagy ( ) sometimes ovophagy, literally "egg eating", is the practice of
embryos feeding on eggs produced by the ovary while still inside the mother's uterus. The word oophagy is formed from the classical Greek (, "egg") and classical Greek (, ...
).
In females, only the right
ovary
The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. ...
appears to function, and it is currently unknown why only one of the organs seems to function.
Gestation
Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregna ...
is thought to span over a year (perhaps two to three years), with a small, though unknown, number of young born fully developed at . Only one pregnant female is known to have been caught; she was carrying six unborn young.
Mating is thought to occur in early summer and birthing in late summer, following the female's movement into shallow waters.
The age of maturity is thought to be between the ages of six and 13 and at a length of . Breeding frequency is thought to be two to four years.
The exact lifespan of the basking shark is unknown, but experts estimate to be about 50 years.
Conservation
Aside from direct catches, by-catches in trawl nets have been one of several threats to basking sharks. In New Zealand, basking sharks had been abundant historically; however, after the mass by-catches recorded in 1990s and 2000s, confirmations of the species became very scarce.
[Basking shark](_blank)
Department of Conservation. govt.nz Management plans have been declared to promote effective conservation. In June 2018 the
Department of Conservation
An environmental ministry is a national or subnational government agency politically responsible for the environment and/or natural resources. Various other names are commonly used to identify such agencies, such as Ministry of the Environment ...
classified the basking shark as "Threatened - Nationally Vulnerable" under the
New Zealand Threat Classification System
The New Zealand Threat Classification System is used by the Department of Conservation to assess conservation priorities of species in New Zealand.
The system was developed because the IUCN Red List, a similar conservation status system, had some ...
.
The eastern north Pacific Ocean population is a U.S.
National Marine Fisheries Service
The National Marine Fisheries Service (NMFS), informally known as NOAA Fisheries, is a United States federal agency within the U.S. Department of Commerce's National Oceanic and Atmospheric Administration (NOAA) that is responsible for the stew ...
species of concern, one of those species about which the U.S. Government's
National Oceanic and Atmospheric Administration
The National Oceanic and Atmospheric Administration (abbreviated as NOAA ) is an United States scientific and regulatory agency within the United States Department of Commerce that forecasts weather, monitors oceanic and atmospheric conditio ...
has some concerns regarding status and threats, but for which insufficient information is available to indicate a need to list the species under the U.S.
Endangered Species Act
The Endangered Species Act of 1973 (ESA or "The Act"; 16 U.S.C. § 1531 et seq.) is the primary law in the United States for protecting imperiled species. Designed to protect critically imperiled species from extinction as a "consequence of ec ...
(ESA).
The
IUCN Red List
The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...
indicates this as an
endangered species
An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...
.
The endangered aspect of this shark was publicised in 2005 with a
postage stamp
A postage stamp is a small piece of paper issued by a post office, postal administration, or other authorized vendors to customers who pay postage (the cost involved in moving, insuring, or registering mail), who then affix the stamp to the fa ...
issued by
Guernsey Post
Guernsey Post is the postal service for the island of Guernsey, Channel Islands. It includes a Philatelic bureau, and regularly issues both Definitive stamp, definitive and Commemorative stamp, commemorative stamps. It also provides postal ser ...
.
Importance to humans
![Basking shark Harper's Weekly October 24, 1868](https://upload.wikimedia.org/wikipedia/commons/f/fe/Basking_shark_Harper%27s_Weekly_October_24%2C_1868.jpg)
Historically, the basking shark has been a staple of fisheries because of its slow swimming speed, placid nature, and previously abundant numbers. Commercially, it was put to many uses: the flesh for food and fishmeal, the hide for
leather
Leather is a strong, flexible and durable material obtained from the tanning, or chemical treatment, of animal skins and hides to prevent decay. The most common leathers come from cattle, sheep, goats, equine animals, buffalo, pigs and hogs, ...
, and its large
liver
The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for ...
(which has a high
squalene
Squalene is an organic compound. It is a triterpenoid with the formula C30H50. It is a colourless oil, although impure samples appear yellow. It was originally obtained from shark liver oil (hence its name, as ''Squalus'' is a genus of sharks). A ...
content) for
oil
An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) & lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturated ...
.
It is currently fished mainly for its fins (for
shark fin soup
Shark fin soup is a traditional soup or stewed dish served in parts of China, Taiwan, and Southeast Asia. The shark fins provide texture, while the taste comes from the other soup ingredients. It is commonly served at special occasions such as ...
). Parts (such as
cartilage
Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck an ...
) are also used in
traditional Chinese medicine
Traditional Chinese medicine (TCM) is an alternative medical practice drawn from traditional medicine in China. It has been described as "fraught with pseudoscience", with the majority of its treatments having no logical mechanism of action ...
and as an
aphrodisiac
An aphrodisiac is a substance that increases sexual desire, sexual attraction, sexual pleasure, or sexual behavior. Substances range from a variety of plants, spices, foods, and synthetic chemicals. Natural aphrodisiacs like cannabis or cocain ...
in Japan, further adding to demand.
As a result of rapidly declining numbers, the basking shark has been protected in some territorial waters and trade in its products is restricted in many countries under
CITES
CITES (shorter name for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of interna ...
. Among others, it is fully protected in the United Kingdom and the Atlantic and Mexican Gulf regions of the United States.
Since 2008, it has been illegal to fish for, or retain if accidentally caught, basking sharks in waters of the European Union.
It is partially protected in Norway and New Zealand, as targeted
commercial fishing
Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often ...
is illegal, but accidental bycatch can be used (in Norway any basking shark caught as bycatch and still alive must be released).
As of March 2010, it was also listed under Annex I of the
CMS
CMS may refer to:
Computing
* Call management system
* CMS-2 (programming language), used by the United States Navy
* Code Morphing Software, a technology used by Transmeta
* Collection management system for a museum collection
* Color manag ...
Migratory Sharks Memorandum of Understanding.
Once considered a nuisance along the
Canadian Pacific coast, basking sharks were the target of a government eradication programme from 1945 to 1970. , efforts were under way to determine whether any sharks still lived in the area and monitor their potential recovery.
It is tolerant of boats and divers approaching it, and may even circle divers, making it an important draw for dive tourism in areas where it is common.
Carcass misidentification
On several occasions, "
globster
A globster or blob is an unidentified organic mass that washes up on the shoreline of an ocean or other body of water. A globster is distinguished from a normal beached carcass by being hard to identify, at least by initial untrained observers, ...
" corpses initially identified by non-scientists as a
sea serpent
A sea serpent or sea dragon is a type of dragon sea monster described in various mythologies, most notably Mesopotamian (Tiamat), Judaeo-Christian (Leviathan), Greek (Cetus, Echidna, Hydra, Scylla), and Norse (Jörmungandr).
Mythology and fo ...
's or
plesiosaur
The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia.
Plesiosaurs first appeared ...
's have later been identified as likely to be the decomposing carcasses of basking sharks, as in the
Stronsay Beast and the ''
Zuiyo-maru'' cases.
See also
*
List of prehistoric cartilaginous fish
This list of prehistoric cartilaginous fish genera is an attempt to create a comprehensive listing of all genera that have ever been included in the class chondrichthyes ''and'' are known from the fossil record. This list excludes purely vernacul ...
*
List of threatened sharks
*
Shark liver oil
Shark liver oil is an oil obtained from the livers of sharks. It has been used for centuries as a folk remedy to promote the healing of wounds and as a remedy for respiratory tract and digestive system problems.
References
;General references
*
*
* David A Ebert, ''Sharks, Rays and Chimaeras of California'',
*
* Marine Conservation Society
Basking shark page* FAO Figi
Species Fact Sheet for basking shark
External links
*
Irish Basking Shark ProjectBBC Wildlife Finder – video news and news from the BBC archiveARKive entry on the Basking Shark*
ttp://www.visitisleofman.com/thingstoseeanddo/wildlife/baskingsharks.xml Basking Sharks in the Isle of Man*
*Basking sharks featured on
RNZ ''
Critter of the Week
''Critter of the Week'' is a weekly RNZ National programme about endangered and neglected native plants and animals of New Zealand.
Beginning in 2015, ''Critter of the Week'' is an approximately 15-minute discussion between Nicola Toki of the ...
''
24 Jan 2020Basking Shark - Videoon Check123 - Video Encyclopedia
{{Authority control
Ovoviviparous fish
Cosmopolitan fish
Basking shark
The basking shark (''Cetorhinus maximus'') is the second-largest living shark and fish, after the whale shark, and one of three plankton-eating shark species, along with the whale shark and megamouth shark. Adults typically reach in leng ...
Taxa named by Johan Ernst Gunnerus
Extant Rupelian first appearances
Taxobox binomials not recognized by IUCN